A few days ago my daughter fished out some giant minis from one of our bins (mostly some fire and frost giants, along with various titans), and after we built a dungeon mostly scaled for them I was surprised to find that I hadn't yet statted any sort of giant for FrankenFourth.

As with most things I started by doing some research, because in the course of writing a bajillion Dungeon World classes, A Sundered World, and other various things I've realized that when it comes to monsters the mythological source has usually been more interesting than the Dungeons & Dragons iteration (and, by association, Dungeon World).

Here's some of what I was able to dig up:

In Greek mythology giants were really strong, but not necessarily really big (good for if I wanna include a super-strong human-ish race option/talent tree), and some representations depicted giants as having snakes for legs. Weird, but different. They also fought against the Olympian gods, so that's something to keep in mind when thinking about giant flavor/background stuff.

The cyclopes were one-eyed giants that were imprisoned and released from Tartarus a few times, and forged magical weapons for some of the Olympian gods. I recall 4th Edition Dungeons & Dragons really playing up this aspect (as well as giving them magic eyes), having them create weapons for the fomorians, but I think it's enough to just say that some cyclopes would be responsible for various magic items (and could even teach characters how to make some, or at least make magic items in exchange for something).

Norse mythology mentions a variety of giants, such as clay, fire, frost, sea, and wind (I'm guessing this is what Dungeons & Dragons used as inspiration for its classic giant roster). Some looked monstrous, with fangs and claws, sometimes even multiple heads or animal shapes (such as Hræsvelgr, who looks like an eagle). Others were described as quite beautiful, and as with Greek giants some were also human-sized and battled against the gods.

Bulgarian giants, known as ispolin, were described as being about 10 feet tall and, depending on the legend, having one huge head, three heads with a single eye each, or one leg. They were said to only eat raw meat, fought dragons, and fear blackberry bushes: they would I guess fall into them, get stuck, and die, and so would offer sacrifices to appease them. Doesn't matter, because in the end they were destroyed by God, who deemed them unsuited for life on Earth.

In European folklore, it was not only believed that giants built the remains of previous civilizations, but sometimes natural features were attributed to their actions. For example the Giant's Causeway, located on the northeast coast of northern Ireland, is an area of nearly 40,000 interlocking basalt columns said to have been built by a giant (but were really formed 50-60 million years ago due to volcanic activity). Even so, looks neat and could easily be dropped into your campaign as something built by a giant:

Interesting stuff, but from what I found not much different from Dungeons & Dragons, which mostly treats them as Large or Huge humanoids. So, I guess mechanically FrankenFourthgiants will be similar, though I'll still put in customization sidebars for giving your giants claw and bite attacks, extra heads, and so on. I couldn't find much in the way of magical/special abilities, which is what I was hoping for because I'm not a fan of the whole nonsense pseudo-Vancian spellcasting thing that some D&D giants have.

This is something I'll change so that, for example, instead of a storm giant being able to cast levitate 2-3 times per day (yawn), they could cause a storm to build up whenever they want (maybe treating it as a ritual effect that takes 10 minutes or so). Channeling a lightning bolt could normally be a recharging thing (or inflict fatigue damage per wizard/sorcerer spellcasting), but in stormy weather they would be able to use it constantly and even fly about.

For now though I'm going to focus on statting out fire giants, since that's what I have the most of (and also a lava-cavern Dwarven Forge set that I've barely used). I can't recall any encounter-building guidelines for 2nd Edition, but checking Editions 3-through-5 I see that your average fire giant is intended to be thrown at the party at roughly the halfway mark of their adventuring career.

FrankenFourth has actually flat math, but for the sake of backwards compatibility pegging them at 10th-level sounds fine by me, and using our monster-making guidelines (and D&D ability score mods) we end up with the following stat block:

OFFENSEMultiattack 2 The fire giant can make two longsword attacks per round.Longsword +10 to hit; 2d8+2d6+7 damage (2 armor piercing).

Fire giants don't have literally fiery beards and hair. Being native to a realm of fire and ash (something at least similar to Muspelheim), they are immune to its effects (smoke doesn't blind them, and they do not choke on it). They tend to be skilled smiths, and would definitely be on a list of creatures to seek out for characters that want to master the weaponsmithing and armorer craft skills. Probably also know rare/unknown craft techniques for even magical items (like flaming swords).

Customization options would include burning blood (targets that deal Wound damage need to make a check to avoid taking fire damage), molten claws, fire/lava/smoke breath (really bad if the giant also has multiple heads), command flames, transforming into fire or lava, splitting the ground open with burning fissures, and conjuring creatures made of fire/lava. Depends on how weird and/or magical you want the giant to be.